What Burns More Calories: lifting weights, cardio, commuting by bike or on foot
Is lifting weights better than cardio for weight loss?
Conventional wisdom says that aerobic exercise (combined with cutting calories) is the best way to lose weight. But millions of people have logged hours on elliptical machines and stationary bikes without dropping any pounds. This means that either (a) losing weight takes a lot more effort than most people expect, or (b) we’ve been misled and there’s a much better way to lose weight. Strength training is often proposed as that “better way”—though the evidence strongly suggests the real answer is (a).
In a head-to-head match-up of an aerobic workout versus a strength workout, there’s no dispute that you’d burn more calories in the aerobic workout (assuming that intensity and duration are held roughly equal). It’s the calories you burn during the rest of the day that might tilt the field in favor of weights. A classic study published in 1977 showed that the gradual decline with age of your resting metabolic rate—the calories you burn just to stay alive, even when you’re sleeping—is due almost entirely to the loss of muscle mass that begins in your mid-30s and continues inexorably for the rest of your life. Pumping iron slows the loss of muscle, or even adds new muscle, which keeps your metabolism ticking a little more quickly.
Strength training also stimulates your body to burn more fat instead of carbohydrate as fuel—though it’s not clear that burning more fat actually reduces the amount of fat you store in the long term. There’s also the simple fact that if you’re strong and healthy, you’re more likely to move around, lift things, climb stairs, and otherwise burn calories in the course of your day-to-day life. It was these factors that convinced the American College of Sports Medicine, in 2009, to acknowledge the possibility that strength training might contribute to weight loss, reversing an earlier official stand. They’re now taking more of a wait-and-see approach—there’s no experimental evidence that these factors make any significant difference, but they at least sound plausible.
There’s no shortage of studies on strength training and weight loss. A typical example, published in the American Journal of Clinical Nutrition in 2007, monitored 164 overweight, middle-aged women for two years. Half of them lifted weights twice a week, the other half were simply given brochures recommending aerobic exercise. The weights group gained about three pounds, including a 7 percent increase in dangerous abdominal fat; the control group gained 4.4 pounds, with a 21 percent spike in abdominal fat. This is clear evidence that strength training is good for you—but not that it’s better than aerobic exercise for weight loss.
The most positive results, not surprisingly, come from studies that combine aerobic and strength exercise. A Korean study that pitted a six-days-a-week aerobic training program against three days each of aerobic and strength training found that the combined program produced the best results for decreasing surface and abdominal fat, as well as increasing muscle mass. There’s no doubt that strength training has innumerable benefits—including, possibly, boosting your metabolism and fat-burning abilities. But for real-world health purposes, it works best in combination with aerobic exercise.
Will I burn more calories commuting by bike or on foot?
Most commuters strive to be as efficient as possible. But to get the best workout—specifically, to burn the most calories—you’re better off being inefficient. Biking three miles to work could burn 130 calories, while walking the same distance would burn 225. Of course, the bike ride would take 15 minutes, while the walk would take close to an hour. If you add a scenic detour to the bike ride so that it takes an hour, you’d burn over 500 calories. (Those numbers are for a 155-pound person biking at 13 miles per hour or walking at three to four miles per hour, both “moderate” paces.)
You’ll need to balance these different types of efficiency—time spent versus energy burned—in order to choose the right mode of transport for your commute. Your decision will also depend on logistical factors like the length of the commute, where there are good bike paths, and whether your workplace has showers. If you’re lucky, you’ll be able to alternate between different options.
• BIKING: The dominant factor in outdoor biking is air resistance, which gets increasingly important the faster you go. It accounts for 90 percent of the resistance you feel at racing speeds above 18 miles per hour. This means that if you bike too slowly it will be even less taxing than a brisk walk. But it also means that cranking up the cadence can quickly make it harder. Hills and frequent stops can also make the bike commute more of a workout. Because of the trade-off between air resistance and gravity, the most time-efficient strategy is to push a bit harder on the uphills (when your speed is already reduced) and recover on the downhills. Biking is the most practical commuting option for any distance beyond a few miles. But it takes conscious effort (along with, perhaps, a shower at work and a detour on the way home) to turn it into a really good workout.
• WALKING: Each of us has an optimal walking speed that feels comfortable and burns the fewest calories per mile. Walking significantly faster than that optimal speed can actually be as fast and calorie-intensive as a very slow run, but it quickly becomes uncomfortable to sustain. That’s why, with all due respect, race-walkers are so funny to watch. It’s important to bear in mind the differences between a brisk walk and a leisurely stroll. You’re burning more than three times as many calories at five miles per hour than you are at two miles per hour. Unlike a gym workout, the length of your commute is determined by distance rather than time. Chalk that up as an advantage for walking, which will make your workout commute the longest—but make it a brisk walk that requires effort.
• RUNNING: There’s a long-standing misconception that propelling yourself on foot from point A to point B takes a set number of calories no matter how fast you move. That idea was finally debunked in a 2004 study in the journal Medicine & Science in Sports & Exercise, which showed that running at 10 minutes per mile burns about twice as many net calories as walking at 20 minutes per mile. The difference comes in part from the up-and-down motion of the running stride. Running offers commuters the perfect mix of a vigorous but time-efficient commute, but it comes with its own logistical challenges. Not only do you have to shower, but you need to organize (and perhaps schlep in a backpack) clothing and possibly lunch, as well as decide how to get home.